Regeneration of an absorbent solution laden with acid compounds is costly, notably as regards energy consumption. This is a major drawback, notably when the absorbent solution is used to capture the CO2 present in combustion fumes. In fact, if the heat required to regenerate the absorbent solution is obtained by combustion of a fossil fuel, an additional amount of CO2 may be produced, which would make the capture of CO2 by absorption uninteresting.
Document FR-2,898,284 aims to heat fractionate the absorbent solution laden with acid compounds into two parts, a part rich in acid compounds and a part poor in acid compounds, and to regenerate by distillation only the fraction that is enriched in acid compounds in order to minimize the energy required for regeneration of the absorbent solution. However, the heating of the absorbent solution generated by the exothermic reaction between the acid compounds and said absorbent solution can possibly cause separation of the absorbent solution into two phases in the absorption column. Such a situation would not allow optimum operating conditions for the process. The formation of two liquid phases in the absorption column would limit the transfer of acid compounds between the gas to be deacidized and the absorbent solution. The acid compounds could no longer be absorbed efficiently by the absorbent solution.
The present invention aims to control the demixing phenomenon in the absorption column by means of one or more cooling operations of the absorbent solution circulating in the absorption column, in order to prevent separation of the phases in the column and to obtain separation of the phases at a later stage of the deacidizing process.